A unity gain buffer may be used to provide high current driving capability while keeping the ratio of output voltage to input voltage close to unity. Desired characteristics for a unity gain buffer design are listed below:                1. Capable of delivering high current to output load.        2. High output switching speed.        3. Output voltage to input voltage ratio close to unity.        4. Low quiescent current.        
However, improving the characteristics numbered 1-3 above generally require high quiescent current, and therefore improving characteristics 1-3 above are generally done at the expense of characteristic 4 (low quiescent current) above.